A silicon nitride film is excellent in terms of not only gas barrier properties but also transparency, and accordingly is widely utilized as a barrier film in the food, medical, and electronics fields. Non-Patent Literature 1 proposes that gas barrier properties of a barrier film are improved by decreasing impurity concentration of the barrier film. Also, Patent Literature 1 proposes that gas barrier properties of a silicon nitride film are improved by decreasing oxygen concentration of the silicon nitride film (paragraph 0018).